JP2005032429A - Slider, and system and method using slider - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system and a method for controlling the floating quantity of a magnetic head located on the upper part of a magnetic storage medium such as a disk. <P>SOLUTION: A charging electric pad can be combined with the slider separated from the magnetic head in order to impress electric charge from a charging conductor to the slider. By allowing the charging electric pad to act as a quasi-parallel capacitor, an interval in a boundary between the head and the disk can be increased/decreased on the basis of an impressed voltage level. The slider may be electrically insulated from a suspension. A feedback control system can monitor and control the interval between the head and the disk by measuring temperature surrounding the slider and the disk or other environmental conditions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

A method for adjusting the floating amount of a magnetic head using an electric charge through an electric pad on a slider is described.
The present invention relates to a magnetic hard disk drive. More specifically, the present invention relates to a method for adjusting the floating amount of a magnetic head on a magnetic storage medium through an electrical pad on a slider.

  A hard disk drive is a common information storage device consisting essentially of a series of rotatable disks or other magnetic storage media accessed by magnetic read and write elements. These data transfer elements, commonly known as transducers, are typically carried by or embedded within a slider body that is held in close relative position on individual data tracks formed on the disk. Enable read and write operations to be performed. In order to properly position the transducer relative to the disk surface, the air bearing surface (ABS) formed on the slider body provides sufficient lift to "fly" the slider and transducer over the disk data track. A flowing air stream is provided. The high speed rotation of the magnetic disk generates an air flow or wind flow along its surface and in a direction substantially parallel to the tangential direction of the disk. The airflow cooperates with the slider body ABS, which allows the slider to fly over a high-speed rotating disk. In practice, this suspended slider is physically separated from the disk surface via its self-actuating air bearing.

  Some of the major goals in ABS design are to make the slider and its associated transducer fly as close as possible to the surface of the rotating disk, and to maintain that constant proximity distance regardless of variable flight conditions. It is to maintain. The height or separation gap between the air bearing slider and the high-speed rotating magnetic disk is generally defined as a floating amount. In general, the attached transducer or read / write element will fly less than about 1 microinches (25.4 nm) on the surface of the rotating disk. Slider float is considered to be one of the most important parameters affecting the magnetic disk read and recording capabilities of the attached read / write element. Due to the relatively small amount of float, the transducer can achieve greater resolution between different data bit locations on the disk surface, thus improving data density and storage capacity. As lightweight compact notebook computers that utilize relatively small and powerful disk drives have become increasingly popular, the demand for gradual reduction in float is increasing.

  As shown in FIG. 1, the known ABS design for a typical catamaran slider 5 is formed with a pair of parallel rails 2 and 4 extending along the outer edge of the slider surface facing the disk. Can do. Other ABS shapes have also been developed, including three or more additional rails with various surface areas and geometries. The two rails 2 and 4 typically run along at least a portion of the length of the slider body from the leading edge 6 to the trailing edge 8. The leading edge 6 is defined as the edge of the slider through which the rotating disk passes as it travels the length of the slider 5 toward the trailing edge 8. As shown, the leading edge 6 is tapered in spite of the large undesired tolerances typically associated with the tapering process. The transducer or magnetic element 7 is typically mounted somewhere along the trailing edge 8 of the slider, as shown in FIG. Rails 2 and 4 form an air bearing surface for the slider to fly above, and are provided with the necessary lift when in contact with the air flow formed by the high speed rotating disk. As the disk rotates, the generated wind or air stream travels along and between the lower surfaces of the catamaran slider rails 2 and 4. As the air flow passes under the rails 2 and 4, the air pressure between the rail and the disk increases, thus creating positive pressure application and lift. Catamaran sliders generally create a sufficient amount of lift or positive load to fly the slider at a suitable height above the rotating disk.

  As illustrated in FIG. 2, the head gimbal assembly 40 gives the slider several degrees of freedom such as a vertical interval, a pitch angle, and a roll angle indicating the floating amount. As shown in FIG. 2, the suspension 74 holds the HGA 40 above the moving disk 76 (having the edge 70 and moving in the direction represented by the arrow 80). During operation of the disk drive shown in FIG. 2, the actuator 72 (eg, voice coil motor (VCM)) can vary the various diameters (eg, inner diameter (ID), intermediate diameter (MD), and outer diameter) of the disk 76 throughout the arc 75. (OD)) Move the HGA above.

  Ideally, the head-disk spacing should remain unchanged at different temperatures. However, the flying height or head-disk spacing changes with environmental temperature variations. The cause of the change in the floating amount is a change in the geometry of the head such as a crown and a camber. At an extremely low temperature, for example, a change in the floating amount can be as large as several nanometers due to a change in the geometrical shape of the head, leading to a decrease in recording performance and a malfunction of the head. In order to solve this problem, two methods have been used to compensate for changes in the floating amount at low temperatures. In one method, a heating coil is provided in the head, thereby protruding the read-write area. The actual head-disk spacing remains unchanged. Since the heating coil is added to the head at the wafer level, this method further complicates the entire manufacturing process. In an alternative method, a high current is passed through the writer to heat the pole area and project it to adjust the floating amount. As can be seen here, both techniques attempt to project the pole tip region. As a result, the minimum floating point moves to the protruding magnetic pole tip region, and the magnetic pole tip region may be left unprotected against contact that may occur due to distortion on the disk surface. is there.

  A system and method for adjusting the floating amount of a magnetic head over a magnetic storage medium such as a disk is disclosed. The charging electrical pad can be coupled to the slider remote from the magnetic head so that the charging conductor can provide charge to the slider. By acting as a quasi-parallel capacitor, the size of the spacing within the head-disk interface can be increased or decreased based on the amount of applied voltage. The slider may be electrically isolated from the suspension. A feedback control system can monitor and control the head-disk spacing by measuring the temperature or other environmental conditions surrounding the slider and disk.

FIG. 3 illustrates one embodiment of a slider and suspension as practiced in the present invention. The slider 5 houses a magnetic read / write head 7 or a magnetic read / write transducer. The interface between the head 7 and the disk 76 can be configured as a quasi-parallel capacitor. The magnetic head 7 acts as an upper electrode, while the magnetic disk 76 acts as a lower electrode. The magnetic head 7 and the magnetic disk 76 are separated by a small air gap. When a low voltage is applied to the head-disk interface (HDI), the floating amount decreases with the applied voltage according to the equation f = kv ² / d ² . The symbol f represents the attractive force between the two electrodes (ie, the head 7 and the disk 76). The symbol k represents a constant value. The symbol v represents the voltage applied to both electrodes or the potential difference of the electrostatic field between the head 7 and the disk 76. The symbol d represents the distance between the head 7 and the disk 76. The above equation shows that d decreases with increasing applied voltage, as required by increased f at higher voltages. In other words, the distance between the head and the disk can be reduced by applying a voltage.

  In one embodiment, the first conductor 310 and the second conductor 320 can couple the magnetic head 7 to the electronic feedback system 330. The first conductor 310 can apply a voltage to the magnetic head 7. The first conductor 310 can be coupled to the slider 5 by adding an electrical pad at the trailing edge of the slider 5 during the wafer process. The electrical pad is isolated from any pad of the slider 5 and is electrically isolated from any such pad. The slider 5 may be electrically insulated from the suspension 74 that is normally grounded. The slider 5 can be coupled to the suspension 74 using an adhesive 340 having a high electrical resistance that does not allow any leakage current to the ground through the suspension 74 when a small voltage is applied to the slider 5. . A floating amount monitoring system or electronic feedback system 330 is incorporated into the disk drive electronics system to accurately control the floating amount individually for each head and prevent possible head-disk contact while the floating amount is reduced. Is possible. The feedback system 330 monitors the head-disk spacing by using a read-back signal transmitted via the second conductor 320. The readback signal may be an amplitude, amplitude modulation or other electrical signal that is sensitive to changes in the head-disk spacing. The readback signal can also include data relating to the temperature or other environmental conditions surrounding the slider 5. The feedback system 330 can control the head-disk spacing by sending an accurate voltage to the slider 5 based on the measured head-disk spacing.

  Referring to FIG. 4, a first embodiment of the present invention is shown. In this embodiment, a slider 401 is shown that includes read and write electrical components on the trailing edge. Bonding pads 409 and 411 are provided on the slider for electrically connecting the read / write electrical components to the electrical components on the suspension 421. In this embodiment, the suspension electrical components include four conductive traces 405, 407 coupled to bonding pads 415, 417 for read / write signals, respectively. In standard suspensions as known in the art, the conductive traces 405, 407 may be built into the suspension 421 or separately in a flexible circuit or the like coupled to the suspension. May be made up. The traces are also electrically coupled to the electrical components of the disk drive (eg, a preamplifier not shown in FIG. 4) that control the reading of data from and writing to the storage media.

  According to this embodiment of the invention, the slider 401 is coupled to the suspension tongue 403 in a conventional manner (eg, using an electrically insulating adhesive). A separate charge bonding pad 413 is provided on the outer surface of the slider 401. The charge bonding pad 413 is electrically connected to the slider 401 through either a conductive path or direct contact built into the head structure. A separate charge pad 420 is provided on the suspension along the charge trace 419 to provide a conductive path to the electronic feedback system 330. When the slider 401 is attached to the tongue 403, the slider bonding pads 409, 411, and 413 can be electrically coupled to the suspension bonding pads 417, 415, and 420 by, for example, a gold ball bonding structure. It is also possible to use electrical connection methods including ultrasonic bonding and soldering.

FIG. 5 is a standard graph of a dynamic electrical test (DET) plotting the change in head-disk spacing versus applied voltage. The change in head-disk spacing was measured by the power width (PW50) at 50% height of the readback signal pulse. PW50 varies linearly with the head-disk spacing. To obtain these measurements, a DC power source was used as the voltage source, and voltages from -2 to +2 volts were used. As shown in the plot, the floating amount (PW50) decreases with the applied voltage, regardless of whether the voltage is positive or negative. For a voltage range of 0-2 volts, the PW50 is about 0.12 μin (0.3 × 10 ⁻² μm) or 0.06 μin (0.15 × 10 ⁻² μm) / volt. Thus, for a float of 0.06 μin, 1 volt is sufficient to compensate, as may occur at low temperature operating conditions.

  One problem with applying charge or voltage at the head-disk interface is the potential for electrostatic damage to giant magnetoresistive (GMR) sensors. Most GMR sensors used in the industry have a threshold of about 5 volts. Therefore, the application of a low voltage such as a voltage of 1 volt or less to the head-disk interface has a low probability of causing electrostatic damage to the GMR sensor.

  While several embodiments have been specifically illustrated and described herein, modifications and variations of the present invention are covered by the above teachings and depart from the spirit and intended scope of the present invention. None will be understood to fall within the scope of the claims.

1 is a perspective view of a slider device having a read / write head known to those skilled in the art. FIG. 1 is a perspective view of a disk drive device known in the art. FIG. FIG. 3 illustrates one embodiment of a slider and suspension as practiced in the present invention. FIG. 4 shows an embodiment of a slider with a charging bonding pad as practiced in the present invention. 6 is a standard graph of Guzik measurement plotting the change in head-disk spacing against applied voltage.

Explanation of symbols

2, 4 Rail 5 Slider 6 Leading edge 7 Magnetic read / write head 8 Trailing edge 40 Head gimbal assembly (HGA)
72 Actuator 74 Suspension 76 Magnetic Disk 310 First Conductor 320 Second Conductor 330 Electronic Feedback System 340 Adhesive 401 Slider 403 Tongue 405, 407 Conductive Trace 409, 411, 413 Slider Bonding Pad 419 Charging Trace 415, 417, 420 Bonding pad for suspension 421 Suspension

Claims (29)

A magnetic head coupled to the slider having a first electrical pad set for reading data from the magnetic storage medium and a second electrical pad set for writing data to the magnetic storage medium;
An electrical pad for charging coupled to the slider separated from the magnetic head;
A charging conductor coupled to the electrical pad to apply a charge to the slider;
A slider comprising:   The slider of claim 1, wherein the charging electrical pad is coupled to a trailing edge of the slider.   The slider of claim 1, wherein the charging electrical pad is coupled to the slider during a wafer manufacturing process.   The slider according to claim 1, wherein the slider is coupled to a suspension.   The slider according to claim 4, wherein the slider is electrically insulated from the suspension.   The slider according to claim 5, wherein the slider is coupled to the suspension using an adhesive having high electrical resistance.   The slider of claim 1 connected to an electronic feedback system, wherein the electronic feedback system monitors environmental conditions of the slider.   The slider according to claim 7, wherein the charging conductor is connected to the electronic feedback system, and the charging conductor applies the charge based on a floating amount of the slider.   The slider according to claim 7, wherein the charging conductor is connected to the electronic feedback system, and the charging conductor applies the charge based on an ambient temperature of the slider.   The slider of claim 1, wherein the charge is in the range of 0.1 to 5 volts. A magnetic storage medium;
Suspension,
A slider coupled to the suspension;
A magnetic head coupled to the slider having a first electrical pad set for reading data from the magnetic storage medium and a second electrical pad set for writing data to the magnetic storage medium;
An electrical pad for charging coupled to the slider separated from the magnetic head;
A charging conductor coupled to the electrical pad to apply a charge to the slider;
A system comprising.   The slider of claim 11, wherein the charging electrical pad is coupled to a trailing edge of the slider.   The system of claim 11, wherein the charging electrical pad is coupled to the slider during a wafer manufacturing process.   The system of claim 11, wherein the slider is electrically isolated from the suspension.   The system of claim 11, wherein the slider is coupled to the suspension using an adhesive having a high electrical resistance.   The system of claim 11, wherein the slider is connected to an electronic feedback system that monitors environmental conditions of the slider.   The system of claim 16, wherein the charging conductor is connected to the electronic feedback system, and the charging conductor applies the charge based on a floating amount of the slider.   The system of claim 16, wherein the charging conductor is connected to the electronic feedback system, and the charging conductor applies the charge based on an ambient temperature of the slider.   The system of claim 11, wherein the charge is in the range of 0.1 to 5 volts. Floating the slider above the magnetic data storage medium, the slider being coupled to a read electrical pad set on the slider and a charging electrical pad electrically isolated from the write electrical pad set; ,
Applying a voltage to a charging electrical pad to create a charge on the slider in relation to the magnetic data storage medium;
A method comprising:   21. The method of claim 20, wherein the charging electrical pad is coupled to a trailing edge of the slider.   21. The method of claim 20, wherein the charging electrical pad is coupled to the slider during a wafer manufacturing process.   The method of claim 20, wherein the slider is coupled to a suspension.   24. The method of claim 23, wherein the slider is electrically isolated from the suspension.   24. The method of claim 23, wherein the slider is coupled to the suspension using an adhesive having a high electrical resistance.   21. The method of claim 20, further comprising monitoring environmental conditions of the slider.   27. The method of claim 26, further comprising applying the charge based on a floating amount of the slider.   27. The method of claim 26, further comprising applying the charge based on an ambient temperature of the slider.   21. The method of claim 20, wherein the charge is in the range of 0.1-5 volts.

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